Ernest William Castine (26 November 1869 – 8 February 1955) was a pastoralist and politician in the State of South Australia.
He was also managing director of Andamooka Pastoral Company running 11,000 square miles (28,000 km2) and was partner with Sidney Kidman in Morney Plains Station in Queensland.
He was selected by the Liberal and Country League to contest the 1933 Legislative Council election for the Midland district in 1933.
[4][5] He was secretary of the Northern Agricultural Society, a member of the board of the Clare and District Hospital.
He married again, to Miss Serena Amanda Castine Warren (his first cousin) around September 1923 in Rawmarsh, Yorkshire, England.